Nonetheless, we effectively eliminate the magnetic shear throughout the volume with a relatively small change to the initial boundary. In Figure REF  we display the initial and optimized boundaries (solid) along with an interior surface at \(\psi /\psi _0 = 0.06\)  (dashed) and the magnetic axis (star). The boundary obtained by optimizing with respect to \(m \le 3\) , \(|n| \le 3\)  (black dashed) is visually indistinguishable from that obtained with \(m \le 10\) , \(|n| \le 10\)  (red solid). We can consider some of the features of the optimized surface in consideration of the expression for the rotational transform near the magnetic axis [1]}, [2]}, which indicates that rotating ellipticity and torsion of the axis contribute to the on-axis transform in a vacuum field. We see that the interior surfaces become slightly more elliptical in order to increase \(\iota \)  near the axis, while the ellipticity of the boundary is slightly decreased, becoming more square. However, the torsion of the magnetic axis is maintained.
